Immunofluorescence labelling for Cx36, Cx40 and peripherin in lamina IX of lumbar spinal cord in rat and mouse. Double labelling is shown in the same fields in pairs of images: A1,A2; B1,B2, etc, through to F1,F2. (A–C) Fields displaying punctate labelling for Cx36 (A1, B1 and C1) in lamina IX show labelling for Cx40 only along blood vessels in rat at PD5 (A2, arrow), and in mouse at PD5 (B2, arrow) and at PD10 (C2, arrow). The image in (A) shows a portion of ventral white matter (delineated by dotted lines) to allow inclusion of an underlying blood vessel as a positive control for labelling of Cx40. (D,E) Labelling of peripherin (D1,E1) and Cx40 (D2,E2) in lamina IX, showing absence of labelling for Cx40 specifically within or among peripherin-positive motoneurons, and association of Cx40 with blood vessels (arrows) in rat (D) and mouse (E) at PD5. (F) Labelling of peripherin (F1) and Cx40 (F2) in lamina IX of adult rat, showing absence of labelling for Cx40 in association with peripherin-positive motoneurons, and association of Cx40 with a blood vessel (F2, arrow).